This patent generally relates to modular structural systems, and more particularly to generally polygonal three-dimensional hubs or connectors used in conjunction with modular structural systems.
Known modular structures generally include frame components or members configured for rapid assembly and disassembly. The frame members are required to (a) provide a durable and stable structure, and (b) be easy to handle and be installable by limited number of persons. The frame members can form a wide variety of shelter frames such as outdoor tents, circus tents, playground equipment, geodesic domes, greenhouses, swimming pool structures, etc. The frame members can also form internal structures, such as furniture, stands, shelving, etc.
Many known modular structural systems utilize and require telescoping members to assemble and disassemble a structure. These telescoping members are costly, complicated manufacture and tend to make the structure less rigid or strong. Some of those systems require inner and outer spring loaded tubes and a bolt or clamp that tightens the members together to form a member having a desired length. Other systems require an internal threaded rod or ball screw that cooperates with an internally threaded member. In operation, when the threaded member is turned relative to the rod or ball screw, the overall length of the member shortens or lengthens. Still other systems require a plurality of internal rods having threaded ends connected by a right angle gear and a second mating gear that couples to a handle, which extends outside of the member to enable an operator to turn the handle and thereby turn the rods to lengthen or shorten the member.
One known structural system disclosed in the above-identified U.S. Pat. No. 6,722,086 provides a modular system for constructing a tubular structure. The disclosed modular system provides for tubular structures to be assembled and disassembled in a direction perpendicular to a centerline of the tubing without having to move the tubing along its centerline. The modular system further allows the tubing to be positioned at various angles and allows curved tubing to be used. In an embodiment, the modular system includes a cylindrical hub and a connector that removably couples to the cylindrical hub. The connector has a first end that couples to the hub and a second that defines a notch. One of the walls of the notch connects to a flange that may extend in one or two directions from the centerline of the connector. The connector and flange removably couple to one end of an adapter, which contains a mating notch, wherein the adapter receives a tube.
Another known structural system disclosed in the above-identified U.S. Pat. No. 6,854,238 provides a modular frameworking system having various apparatuses and methods of attaching same. The disclosed framework includes a plurality of hubs which each include a plurality of pairs of opposing flat faces. Each face connects, in turn, to at least one connector. The disclosed frameworking system includes primary “T” shaped connectors that attach directly to the hubs and secondary “L” shaped connectors that attach to the primary connectors and thus the hub. An adapter is provided and connects at one end to a leg of the connector and at the other end to a structural member, e.g., a straight or curved tube, angle or channel. The adapter and structural member are readily removable from the hub and the connector. The connector can be curved and alternatively includes a hinge so that the connector can rotate. The connectors can attach to each face of the hub and can be rotated in multiple directions on any given face of the hub.
U.S. patent application Ser. No. 11/458,321, discloses spherical hubs, which make possible a variety of enclosed, three-dimensional structure. These structures, however, are somewhat limited because of the fairly wide space required to accommodate each node, and thus do not allow for more than a few spokes for each node. While each of these structural systems provides apparatuses and methods for assembling and constructing modular frameworks and structures, it would be desirable to provide a hub or core design that can further increase the flexibility and utility of these systems. Further, it would be desirable for the flexible hub to be simple and inexpensive to manufacture, thereby reducing the overall cost of the structural system in which it is utilized.